Due to its excellent expansion and compression characteristics, elastic fiber is widely used in elastic fabric applications such as legwear, innerwear and sportswear, sanitary applications such as paper diapers and sanitary napkins, and industrial materials applications.
Among such elastic fibers, polyurethane elastic yarn which has high strength and ductility, high recoverability, high chemical resistance and high heat resistance has been sought. In order to expand the use of such polyurethane elastic yarn into new applications, techniques by bonding, rather than blending, a compound having various functions with polyurethane have been developed, to produce polyurethane elastic yarn which has the characteristics of both.
Conventional production techniques of such polyurethane elastic yarn in which compounds of various functions are bonded include, for example, a technique whereby functional polyurethane fiber is obtained, which, as its main chain, has polyurethane obtained by reacting diisocyanate and at least one type of diol having at least one double bond in the molecule, and, as a side chain, has a functional monomer having a vinyl group which was bonded to this main chain by graft polymerization (refer to patent document 1).
However, in the method disclosed in patent document 1, recoverability and heat resistance are insufficient, and in particular, when used in fabrics blended with polyester which require a weight reduction process, there are cases where use is limited because chemical resistance is insufficient, or because the permanent set is large at low temperatures. There are also cases where use is limited because the polyurethane elastic yarn itself is yellow in color.
In addition, a technique has also been proposed whereby polyurethane having excellent insulation characteristics and water resistance which can be used in electronic bridges is obtained by producing thermoplastic polyurethane using polybutadiene polyol containing at least 50 mol % 1,2-vinyl (patent document 2) groups. However, in the method disclosed in patent document 2, the obtained polyurethane is thermoplastic polyurethane, and as a result, it cannot be made into fibers by spinning and is not within the objective of the present invention.